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W. W. MACFARREN AND T. W. GRAY.

GAS ENGINE.

APPLICAHON FILED MAR. 3, l9l9.

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INVENTORS W. W. MACFARREN AND W. GRAY.

GAS ENGINE. APPLICATION FILED MAR. 3, I919- Patbntd Mar. 1, 1921.

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INVENTORS UNITED STATES PATENT OFFICE.

WALTER W. MACFARREN, OF PITTSBURGH, AND'THOMAS W. GRAY, 0F HEIDLEBERG,PENNSYLVANIA, ASSIGNORS TO SAID WALTER W. MACFARREN, TRUSTEE.

GAS-ENGINE.

Specification of Letters Patent.

7 Application filed March 3, 1919. Serial No. 280,261.

To all whom it may concern Be it known that we, WVAL'rnR WV. MAO- FARRENand THOMAS W. GRAY, citizens of the United States, residing,respectively, at Pittsburgh and Heidleberg, in the county of Allegheny,State ottPennsylvania, have invented certain new and useful Improvementsin Gas-Engines, of which the following is a specification.

Our invention relates to internal combusion engines and more especiallyto those working on the four stroke cycle. Our improved engine may beconstructed with any desired number of cylinders but is herein shownwith four cylinders.

The objects oi. our invention are:

let. To produce a 4 cycle engine in which each cylinder will fire ateach revolution instead of once in every. two revolutions as usual,whereby the power output is approximately doubled.

2nd. To increase the piston speed without increasing the speed of theshaft, whereby the heat loss to thewater jacket is lessened and theefiiciency increased.

3rd. To reduce the weight of the reciproeating parts by eliminating theconnecting rods. 1

4th. To eliminate the crank shaft and substitute therefor a straightshaft which may be conveniently mounted in antifriction bearings.

5th. To substitute vfor the cranks, cams which may be designed to obtainmore efiicient control of the motion of the piston.

6th. To provide a direct contactingdevice between each piston and itscam by which power is transmitted from piston to shaft and vice versa.

7th. To provide a cushioning device to control the outer reversal of thepiston.

8th. To v provide a differential piston stroke whereby the lengths ofthe power,

exhaust, inlet and compression strokes can be separately best adaptedfor their respective functions.

9th. To provide automatic means for maintaining the fluid pressurepistoncushion at maximum effectiveness.

10th. And to provide various detailed improvements in the design andconstruction of such engines whereby they may be made more satisfactoryand efficient.

Referring to the dra'wing'sf Figure 1 is a sectional side elevation ofour improved engmc. Fig. 2 is a transverse cross section of the same,and Fig. 3 is a view similar to Fig. 2, showing a modified form ofengine.

The shaft 1 is mounted in a split crank case having an upper. part 2 anda lower part 3, and is provided with a cam 41 for each cylinder. Thecylinders 5 have each an upper bore 6 and a lower bore? in which thereworks atwo diameter piston 8 with upper piston rings 9 engagingthe upperbore 6 and lower piston rings 10 engaging the lower bore 7.

A cylinder head 11 is provided with inlet valves 12 and exhaust valves13 both of which may be of any desired construction and operated in anydesired manner. An inlet manifold 14 supplies gas to the cylinders andthe exhaust passes out through an exhaust manifold 15. The clearance volume 16 above the upper piston 8 is the space in which the explosiontakes place. Power is transmitted from the piston 8 to the cam 4 througha roller 17 mounted on a pin 18 secured to the lower end of the piston8. Asshown in Fig. 2 the engine is on the dead center and may besupposed to be just starting a power stroke in eitherv direction ofrotation, it being understood of course that the cam 41 is carriedaround by the momentum of the connected moving parts.

.As soon as the high point 19 passes the center line of the engine thepiston 8 moves downward under the force ofv the exploding gases and theroller 17 exerts pressure on the cam 41. toturn it until the low point20is in contact with the roller 17, when the piston hasreached the bottomof its stroke. As the cam continues to revolve the part between 20 and21 bearing against the roller 17 will force it upward,,thus giving thepiston an up or exhaust stroke. 7

During the quarter turn from 21 to 22 the piston may travel downwardagain on its inlet stroke, and during the quarter turn from 22 to 19 thepiston 8 will be forced upward by the cam 4 on its compression stroke.

In a vertical engine at slow speed the above described operation wouldtake place by the force of gravity acting on thepiston 8, but at highspeed it requires an additional limit of its travel on the exhauststroke. It

Patented Mar. 1, 1921.

is also of advantage to have a positive check on the upper motion of thepiston during the compression stroke as in case of a valve stickingthere would no compression ob tained.

To obtain this necessary force we have provided a cushioning deviceacting on the upper side of the enlarged lower portion of the piston 8,and comprising a manifold 23 which forms a small reservoir forcompressed gas or air. This manifold as shown in Fig. 2 is supplied withpressure from the exhaust manifold through a pipe 2i which leads througha reducing valve 25, to

a second ipe 26 connected with the manifold 23. he reducing valve can besetto maintain a constant pressure in the manitold 23 below that of theexhaust from the manifold 15. A port 27 leads into the upper end of theenlarged bore 7.

As there is at all times a constant pressure in the manifold 23 theupward mo vcment of the piston or pistons is resisted thereby. and it isa matter of designing skill to so an range the area of the lower annularpiston. and the pressure carried in manifold 23 in such proportion tothe speed of the ei'igine and the weight of the piston. to keep theroller 17 at all times in contact with the cam 4.

\Vhen the engine is built with only one cylinder the manifold is simplyan air spring. the air passing in opposite directions through the port27 as the piston moves up or down.

n the preferred construction a a nuilticylinder engine having fourcylinders as shown, two of the pistons move down as the other two moveup, and thus the air is displaced by the upward moving pistons to supplythe downward moving pistons. In either case there will be a certainamount of leakage past the rings 10. and to take care of this somepressure producing device is necessary. .As the PI'ESSJIG of the exhaustis considerable this may in some cases be used as just described. and bythe use of a reducing valve this pressure is made constant in thereservoir as soon as there is any drop in. pressure the valve admitsmore gas.

Tn Fig. i?- we have illustrated a similar arrangement in which thepressure is taken from the interior of the power cylinder itself insteadof from the exhaust. By this means a much higher pressure can beobtained.

in passing it will be noted that by reason of the sealing efi'ect of therings 10 at the lower part of the piston 9. copious splash lubricationmay be used in the crank case. as no considerable quantity of oil canleak upward past these rings due to the existence of a constant pressureabove them.

In Fig. 2 we have shown the cams 4 as symmetrical and of substantiallyelliptical form. It will be understood. however, that since eachquadrant of the cam represents a stroke of the piston itcan beindividually shaped to obtain the most advantageous acpelled by itsmovement n'actically all the products of combustion.

The following stroke will be an inlet stroke, during which the rollerwill travel on the cam 28 from point 3 to point 32. This stroke will beof equal length to the exhaust stroke and will draw in a charge whichwill practically fill the piston displacement plus the clearance volume.

As the cam continues to revolve the roller 30 will travel from point 32to point 34 and the piston 33 will move upward on a coin- 'iressionstroke. However, this stroke will be shorter than the exhaust and inletstrokes because the distance from the center of the shaft 2-9 to thepoint 341 of the cam is less than the corresponding distance to thepoint ill. On the following or power stroke the piston will traveldownward and the roller will roll from point 34 to point 25. As shownthe upper or longer half of the cam controls the inlet and exhauststrokes. and the lower or shorter half of the cam controls thecompression and power strokes.

The advantages of this differential movement of the piston are wellknown, as the cylinder is completely scavenged of burned gases at eachcycle, and draws in a full and unadulterated charge of fresh gas. Thelength of stroke required to give the proper clearance volume andcompression, and the proper length of power stroke may be varied at willby changing the dimensions of the cam.

The cams 28 are also shown as being of substantial elliptical contour.but as before stated. each quarter of the cam may be made of any shapedesired. It will be noted that the symmetrical cam shown at 4 is inperfect balance. whereas an unsymmetrical cam as shown at 28 is out ofbalance; this may be corrected however by forming an opening at 40 ofsuch a size and at such a distance from the center as to make a runningbalance.

In the preferred construction of a four cvlin der engine the outer twocams are placed at right angles to the inner two cams as shown in Figs.1 and 2; thus the movement of the outer pistons is exactly the same andis opposed to the movement of the inner pistons. As the pistonsmay bemade of exactly equal weights, this produces a very efliclent runningbalance. If in addition the cams are symmetrical or balanced with eachother, the whole engine will be well balanced. Further, since the camsare of considerable size and weight, the necessity for a fly wheel maybe in many casesdispensed with. i i I In order to prevent the rotationof.the

pistons and keep the roller pins18 in proper possible with crank shaftsat the ends only,

whereas with our construction a bearing may be put between each pair ofcams if desired.

The. valve mechanism, drive therefor, ignition system, and carburetorhave not been described in detail, as they form no part of thisinvention. 4 The outstanding difference between this engine and otherfour cycle engines is the fact that a complete cycle of four pistonstrokes is obtained for each revolution of the shaft. By this means thepower at the same shaft speed is approximately doubled, and if thescavenging eflect illustrated in Fig. 3 is also used the power will bemore than doubled. In addition to this, the efiiciency will be increasedby reducing the heat loss to the water jacketor other cooling means,this loss being to a great extent dependent upon the speed of thepiston, it being well known that high speed engines lose a lessproportion to the jacket than low speed ones.

It will be obvious to those skilled in the art that our improved enginemay be built as a. V type motor of eight cylinders by using two fourcylinder blocks as illustrated and setting them at with each other toopcrate on a single shaft having four cams, each cam receiving powerfrom two cylinders. Twelve or sixteen cylinder motors could be similarlybuilt on a four cam shaft.

We claim as our invention:

1. In an internal combustion engine, a power cylinder, a power pistonworking therein, a shaft, a cam on said shaft, a contacting devicecarried by said piston and engaging said cam, and a pneumatic cushioningdevice comprising an enlarged cylinder below the power cylinder andconcentric therewith, an annular flange formed at the lower end of thepiston and working in therein, a shaft, a cam on said shaft, acontacting device carried by said piston and en gaging said cam,and apneumatic cushioning device for cushioning the piston on its in stroke,including a reservoir, means for charging said reservoir with pressuregenerated in the power cylinder, and means for maintaining asubstantially constant pressure in said reservoir. v

4. In an internal combustion engine, a

power cylinder, a power piston working therein, a shaft, a cam on saidshaft, acontacting device carried by said piston and engagingsaid cam,and a pneumaticcushioning device including a reservoir, for cushioningthe piston on its upstroke.

5. In an internal combustion engine, four parallel cylinders, a shaft, apower piston in each cylinder, an oval cam on the shaft for eachcylinder, the two outer of said cams having their long diameters at aright angle to the long diameters of the two inner cams, and acontacting device for each piston en gaging its cam, in combination withan enlarged cushioning cylinder below each power cylinder, a flange atthe bottom of each power piston working in said enlarged cylinder, anair reservoir, and a port connecting each of said cushioning cylinderswith said reservoir.

6. In an internal combustion engine, a cylinder, a piston, a shaft, acam thereon, a contacting device on said piston engaging said cam, apneumatic spring cooperating with said contacting device to cushion thepiston on its upstroke, a source of pressure, and a connection betweenthe same and said spring device.

7. In an internal combustion engine having four cylinders, each of saidcylinders having a smaller and a larger bore, stepped pistons working insaid cylinders, a shaft, a cam on said shaft for each of said cylinders,and a contacting device on each of said pistons toengage one of saidcams, a fluid pressure manifold, and a port leading from the larger boreof each of said cylinders to the said manifold, the whole arranged sothat two of said pistons move oppositely to the other two whereby theworkdone by the fluid pressure against two of said pistons is balancedby the work done against the fluid pressure by the other two pistons.

8. In an internal combustion engine, a

cylinder, {rs-piston, a shaft, a cam on said. shaft, a contacting deviceon said piston engaging said camwvhereby the movement of the piston isdetermined by the contour of the cam, a fluid pressure device formaintaining the engagement of the contacting device with the cam, and apipe connecting the combustion space in the cylinder with the fluidpressure device to supply the same with fluid pressure.

' 9. In an internal combustion engine having a plurality of cylinders, apiston for each cylinder, a shaft, a cam on said shaft for each of saidpistons, a contacting device on each piston engaging its co-acting cam,whereby the movement of each piston is determined by the contour of itscam, a fluid pressure device for each piston to maintain the engagementof its contacting device with its cam, a manifold connecting thepneumatic devices for all the pistons, and a pipe connecting thecombustion space in one of the cylinders with said manifold to supplypressure thereto.

10. In an internal combustion engine, a cylinder, a piston, a shaft, acam on said s aft, a contacting device on said piston engaging said camto drive the same, and a pneumatic cushioning device in line with saidcylinder and cooperating with said piston to maintain the engagement ofsaid cam with the contacting device on the piston.

11. In an internal combustion engine, a cylinder, a piston, a shaft, acam on said shaft, a contacting device on said piston engaging said camto drive the same, and a pneumatic cushioning device concentric withsaid cylinder and cooperating to maintain the engagement of saidcontacting device and said cam.

12. In an internal combustion engine, a plurality of cylinders, a shaft,a cam on said shaft for each of said cylinders, a piston for eachcylinder, a roller on each piston engag ing one of said cams, anindividual pneumatic cushioning device for each of said pistons tomaintain the engagement of said roller and said cam, and means forsupplying pressure to said cushioning devices from a common source ofsupply.

In testimony whereof we hereunto afiix our signatures in the presence ofa witness. f

W. W. MACFARREN. THOMAS W. GRAY.

Witness.

A. M. Goonwm.

